A variety of animal species, principally rats and monkeys will be chronically exposed to ozone at concentrations in the high ambient range (0.2-0.8 ppm). A multidisciplinary group will make integrated biochemical, bacteriological, physiological and pathological evaluations of effects. The findings will have relevance to the specific problem of air pollution and to a general understanding of pulmonary pathobiology. By plotting the relative levels of sensitivity of the various parameters studied and the effects observed, a basis will be provided for making predictions of possible long-term consequences of photochemical smog on man. Comparison of effects in rats, monkeys and species such as dogs and cats should provide for more confident extrapolation to man and hence enable the setting of rational air quality criteria. A primary goal is to test critical hypothesis concerning biochemical, and cellular mechanisms responsible for the deleterious effects of the pollutants. Major pathogenetic and modifying factors of interest are: the role of lipid peroxidation in initiating damage; the phenomenon of adaptation; the sites of impairment in pulmonary alveolar macrophages; the sequence and nature of lesions resulting in the development of chronic obstructive pulmonary disease (bronchitis/emphysema) and interstitial fibrosis. An additional goal is to explore further the potential prophylactic value for human populations of dietary antioxidants and trace element selenium.